Heavy showers left the streets of Isla Vista nearly deserted Friday night. (Zack Warburg / Noozhawk photo)

Mother Nature did what hundreds of law-enforcement officers were hoping to do Friday night — keep a damper on the potentially rowdy Halloween celebration in Isla Vista.

A downpour that dropped nearly an inch of rain in a 3-hour period left the streets of the community adjacent to UC Santa Barbara nearly deserted through much of the evening.

“Of all the Halloweens we’ve been to, this was the biggest washout,” said Mike Eliason, a spokesman for the Santa Barbara County Fire Department. “There was nobody on the streets.”

University officials and local law-enforcement officials were hoping for the best but had planned for the worst, with the potential of some 30,000 revelers taking to the streets for Isla Vista’s raucous annual Halloween street party.

A huge contingent of emergency personnel had taken up positions in the seaside community, with the shared goal of ensuring a safe holiday celebration.

Past years had seen scores of arrests and citations, as well as people being hospitalized for various injuries and alcohol poisoning.

The Santa Barbara County Sheriff’s Department’s armored vehicle stands ready by unused Friday night as Isla Vista’s Halloween party is washed out by the season’s first rain storm. (Zack Warburg / Noozhawk photo)

But rain started falling at about 8 p.m. Friday, driving most of the crowds indoors.

“Everybody is inside having their parties,” Eliason said, noting that he was able to easily drive down Del Playa Drive, which typically is impassible on Halloween night due to the giant throngs of costumed young people.

Kelly Hoover, a spokeswoman for the Santa Barbara County Sheriff’s Department, offered a similar assessment.

“The rain definitely made things a lot more quiet,” Hoover said.

The Isla Vista Theater was flooded Friday during a downpour that put a major damper on Isla Vista’s typically rowdy Halloween celebration. (Mike Eliason / Santa Barbara County Fire Department photo)

By 11 p.m., the rain was easing, and both Hoover and Eliason noted that more people had begun heading out onto the streets.

Officials also were waiting to see what happened after a concert staged at UCSB’s Events Center ended at about 2 a.m.

But all indications were that the season’s first significant storm had washed away any chance of the kind of street violence that flared during some past Halloween celebrations, as well as during the Deltopia street party in April.

The rain did cause some other problems, including minor urban street flooding and power outages throughout the South Coast.

The Isla Vista Theater was flooded to the second row of seats after nearby drains clogged, Eliason said, and a large tree limb crashed to the street at Trigo Road and Embarcadero del Mar, blocking traffic.

No injuries were reported.

While a significant contingent of emergency personnel remained in Isla Vista late Friday night, many of the extra officers who had been brought in to help police the streets had been released, Hoover said.

Despite Friday night’s fortuitous outcome, officials know they are not out of the woods, as Saturday night offers another chance for Halloween revelers to take to the streets en masse.

No rain is expected Saturday night, and officials were concerned that they will have to deal with the pent-up desires of Isla Vistans to have their Halloween party.

“It may be possibly even a larger turnout just because they were not able to participate tonight,” Hoover said. “I think everyone recognizes that the weather played a big part in why we didn’t have a big night tonight.”

Emergency personnel plan to have full staffing again Saturday night, Hoover said, but hope that the celebration will remain smaller and more local than in recent years.

Noozhawk executive editor Tom Bolton can be reached at tbolton@noozhawk.com. Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.

A large tree limb broke loose Friday night, blocking traffic at Trigo Road and Embarcadero del Mar in Isla Vista. (Mike Eliason / Santa Barbara County Fire Department photo)